JPS5948857B2 - antifriction alloy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an anti-friction alloy consisting of iron, molybdenum and sulfur.

Compositions of this type that have been proposed hitherto have not been completely satisfactory: they have therefore not been able to be completely freed from the concomitant use of conventional lubricants, in particular oils or fats, etc. This is especially a hindrance in some areas such as chemical engineering, aerospace engineering, and the textile industry.

In addition, it is not possible to guarantee an extremely low coefficient of friction due to operation under unstable lubrication. In particular, these materials consisting of iron, molybdenum, and sulfur do not give better results than solid lubricants such as molybdenum disulfide, tungsten diselenide, graphite, or plastics, and their applications are therefore limited. Plastics, on the other hand, lose their properties when the temperature rises. The present invention is an antifriction alloy consisting of iron, molybdenum, and sulfur, and its composition makes it possible to obtain friction properties with an extremely low coefficient of friction over the entire material even in dry conditions. aim at something.

The gist of the present invention is to provide an anti-friction alloy consisting of iron, molybdenum and sulfur which exhibits extremely low coefficient of friction throughout the material even in a dry state, with a weight composition of iron 8.0-26. 6%, molybdenum 41.0
-62.5%, sulfur 23.3-40.5%, and corresponds to the composition FeXMO3+YS4 (where X does not include 0 and is 1 or less, and y is from 0 to less than 1). Anti-friction alloys, characterized in that they contain at least one dispersed phase in the material and are suitable for reacting under the frictional effect with a mating material to form a corresponding sulfide on the surface of the mating material. .

This composition corresponds to a limited area (less than 5% of the total area of the phase diagram) of the iron-molybdenum-sulfur ternary phase diagram, and surprisingly exhibits excellent frictional properties with extremely low friction coefficient values even in dry conditions. have One of the dispersed phases in this matrix may be the compound FeMO2S4 or the epsilon phase of the iron-molybdenum-sulfur phase diagram: FeMO2.

According to the invention, the alloy is obtained, in particular, by chemical reaction between iron, molybdenum and sulfur onto a substrate, or by melting or vacuum deposition methods or by spraying a powder mixture onto the substrate using a metal spraying torch.

The alloy according to the invention can also be formed by powder metallurgy. They can also be incorporated as fillers in metal or polymer matrices or lubricants. If friction in dry conditions or in a lubricated environment is a problem, the person skilled in the art has conventionally tried as much as possible to reduce the risk of heat generation and seizure, on the one hand, and to improve the efficiency of the friction mechanism, on the other hand. Requires low coefficient of friction.

In the area of dry friction, most rely on solid lubricant type solutions such as graphite, molybdenum disulfide, Teflon coatings, etc.

These solutions make it possible to significantly lower the coefficient of friction, reducing wear and thus increasing the efficiency of mechanisms adjusted in this way. Contributes to improving. However, this type of solution also has a variety of methods, from inability to apply high loads and/or high speeds, from unstable use, and from sticking to surfaces, particularly those more similar to paint or coaters than galvanized. There is something. Third, the lubrication performance obtained using oil-type fluids is not as good as on the left, and even when molybdenum disulfide is used, it "falls off" from the surface in the presence of oil.
lubrication performance is not improved. According to the invention, Fe
, the composition of MO-based alloys can achieve low coefficients of friction in the dry state, hitherto unobtainable.

If the load, speed, other party, and environmental conditions are the same,
The Fe-MO-S composition of the present invention provides a coefficient of friction that is approximately half that obtained with graphite or molybdenum disulfide type coatings. However, the inventors have discovered that only compositions that fall within a specific region of the Fe-MO-S ternary phase diagram make it possible to achieve this type of low coefficient of friction.

Outside this region, especially in the region exhibiting compositions such as those of the compounds FeS, MOS2, it has been found that the friction coefficients obtained for the same friction conditions are at least twice as large as those of the compounds of the invention. Therefore, for example, 10 μ of FeMO2S4 (Fe
8. O-26.6%, MO4l. O-62.5%, S2
A steel plate of XC34 coated with a compound (within a region defined by a composition of 3.3-40.5%) is rubbed, the load of pressing the steel pipe against the plate is 360 kg/♂, and the rotational speed of the steel pipe is increased. If it is 0.55m/S, the friction coefficient obtained in air is 0.04-{). It is 05. Under the same conditions, 0.1 for graphite coating on steel plate, 0.10-0.12 for Teflon coating, and 0.0 for MOS2 coating.
The friction coefficient is 8. Similarly, Fe-MO-S of the present invention
All compositions outside the region of the ternary phase diagram have friction coefficients of 0.08 or more under the same conditions as described above. It should be noted moreover that the compositions of the invention can be used in the presence of oil without shedding phenomena. In the case of the present invention, even if the oil lubrication is unstable, the damage to the lubricated surface is considerably reduced and the obtained friction coefficient is low for the Fe-MO-S coating of the present invention, i.e. the friction coefficient is small. The more damage to the lubricated surface is reduced. Below, examples of the present invention are attached Nos. 1 to 4.
This will be described in more detail based on the diagram.

The present inventor developed the present invention from research conducted on the friction of ternary alloys consisting of iron, molybdenum, and sulfur.

This study revealed that the iron-molybdenum-sulfur ternary state (Fig. 1)
An alloy with a composition located within an extremely limited region that occupies only 4.8% of the total area of the phase diagram expressed by the area of ABCDEF (Figures 2 and 3) exhibits completely unexpected behavior. revealed. When a material with this composition rubs against some kind of mating material, X-ray diffraction proves that this mating material is mostly coated with a layer of sulfide of the mating metal. It was done.

For example, when the other metal is iron, it is coated with iron sulfide FeS. For nickel, nickel sulfide NiS
covered by. Once this coating has been formed, even within the first few seconds of relative movement, the coefficient of friction, even in the dry state, has a very low value, for example less than half of that obtained with molybdenum disulfide. Hexagon AB
The proportions of iron, molybdenum and sulfur which define the area of the CDEF are precisely represented in Figures 2 and 3, but the composition of each point is as follows; that is, this area is a hexagonal shape corresponding to the following proportions: In ABCDEF: Iron 8.0-26.6
%, molybdenum 41. (g)-62.5%, sulfur 23.
3-40.5% o The material according to the invention mainly contains the compound T
It is a multiphase solid consisting of lFeMO2S4 and a solid solution corresponding to the formula T2=FeXMO3+YS4.

Further, the intermetallic compound ε having a specific composition may be contained in various amounts. However, alloys containing only the phase indicated by the point T1 corresponding to the specific compound FeMO2S4 and the triangle T2 corresponding to the solid solution FeXMO3+YS4 are also part of the invention. The composition of the material within the region ABCDEF can be judiciously chosen to bring its properties, in particular its mechanical properties and corrosion resistance, to any desired value without any influence on its frictional properties.

In particular, the presence of the intermetallic compound ε makes the material extremely hard and also significantly increases its corrosion resistance, approaching these properties of molybdenum. Besides the compounds FeMO2S4 and/or the solid solution FeXMO3+YS4, this material can also contain the specific compounds FeS and MOS2.

FIG. 3 shows the range of existence of these various compounds. Even in the dry state, the coefficient of friction values remain very low and are much lower than those obtained using iron sulfide or molybdenum disulfide alone. FIG. 4 is a micrograph showing, without limitation, an example of the present invention using a rematrix FeXMO3+YS4.
FeMO2S4 phase (white dots) dispersed in the (gray background) can be seen.

The sunspots correspond to the stomata. The anti-friction material does not contain free iron or free molybdenum.

It can be ground into powder and incorporated as a filler in other sintered materials such as iron or polymers or in lubricants such as conventional oils or fats. Similarly, since its mechanical properties are close to those of metals, it can be used in the solid state, and its production can be by casting or by powder metallurgy, especially sintering, hot pressing or hot isostatic pressing, or also by hot pressing. by extrusion or any other forming method, and by plating or by metal spraying or vacuum deposition or by any other surface treatment method suitable for mechanical parts of up to several microns. It can also be used to obtain a thick layer. This is not possible with conventional solid lubricants since their mechanical properties are such that if the layer thickness exceeds a few microns, they are immediately removed in the contact area or are too brittle and are destroyed. It is. In all cases iron, molybdenum and sulfur must be chemically combined.

If the production of this material is to pass through an intermediate powder state, a well-mixed mixture of the three elements must be obtained by heating to a temperature sufficient for bonding to occur, melting or not melting. The manufacturing method used in other cases must allow this bonding to occur in a sulfur-containing reactive atmosphere. be.

Example 1 Iron, molybdenum and sulfur powders are mixed in a ratio of 19% iron, 55% molybdenum and 26% sulfur (represented by point 1 in Figures 2 and 3).

This mixture is heated to 800°C. At this temperature, a bonding reaction proceeds between these three elements. The resulting product was then crushed to a uniform level and compressed under a pressure of 4000 kg/Cnl2 into parallelepiped platelets with dimensions of 18 x 30 x 8 mm, followed by heating at 1100° C. for 4 hours in an argon atmosphere. keep. The hardness of this board is about 480VH under a load of 50g
It is. This plate was then subjected to a load of 36 kg/CIn2,
A ring of 35 mm in diameter made of case hardened and tempered 16NC6 steel (0.16% carbon, 1.5% nickel and 0.9% chromium) was rotated around its center line at a speed of 1.1 m/s. When we brought them into contact and recorded the friction coefficient at that time,
It was confirmed that the value was constant at 0.035.

After 5 hours of testing, the specimens are removed and weighed.

The weight loss is 0.5 mg. The other ring is colored black, and X-ray analysis shows that it is covered with an extremely thin layer of iron sulfide, FeS.

Under the same test conditions, a semi-hardened carbon steel plate sprayed with molybdenum disulfide using an aerosol cylinder has a constant friction coefficient of 0.08.
It is.

Example 2 A 45μ thick iron-molybdenum-sulfur alloy layer was deposited on a platelet of XC38 steel (0.38% carbon) with 22.7% by weight of iron and molybdenum JMoV. 3% by weight and hydrogen sulfide 1
Deposited by magnetron reactive cathode sputtering from a residual atmosphere containing 0-4 Torr.

During this deposition process, the substrate was heated to 600°C. heat. The radiation crystal analysis of this layer shows that the composition Fe corresponds to the value of x = 0.8, y = 0.2 of the formula FeXMO3 + YS4.
It showed the presence of ε phase dispersed in the MO4S5 substrate.

Quantitative analysis of the deposit revealed that it was 15.5% iron and 6% molybdenum.
1.2% and 23.3% sulfur.

This composition is illustrated by point 2 in FIGS. 2 and 3. The Bitkers hardness of the formed layer at a load of 50 g is approximately. It is 650HV.

The platelets coated in this way also show no surface deterioration after being exposed to salt spray for 100 hours. The platelets were coated with steel coated with a 20 μm thick layer of nickel chemically applied under the test conditions described in Example 1. The coefficient of friction measured during the hand wheel friction test was constant and equal to 0.02, and the degree of wear after the 2 hour test was 0.1 mg.

Under the same conditions, a test consisting of a platelet of iron-molybdenum-sulfur alloy with a composition of 40% iron, 39% molybdenum, and 21% sulfur had a friction coefficient of 0.18 and a wear of 53 mg after 2 hours of testing. Ta.

Example 3 The composition represented by point 3 in Figures 2 and 3, i.e. iron 17
%, 55% molybdenum and 28% sulfur, an iron-molybdenum-sulfur alloy is prepared by the method described in Example 1.

This compound was finely crushed and mixed into iron powder at a ratio of 85% iron and 15% iron-molybdenum-sulfur alloy, and 4500kg/
Parallelepiped platelets are formed by compression under a Cwf load and heated to a temperature of 1100° C. for 2 hours in an argon atmosphere. The coefficient of friction measured during the test under the test conditions described in Example 1 above was constant and equal to 0.045, and the wear after the 2 hour test was 0.2 mg.

A mixture of 85% iron and 15% molybdenum disulfide was compressed and heated under the same conditions and tested, and the coefficient of friction was 0.085.
The wear after the hour test was 17.6 mg.

Example 4 The same iron-molybdenum-sulfur alloy as in Example 3 is finely ground to produce a powder with a particle size not exceeding 50 microns.

This powder is then mixed with 1 part of neutral oil (26 parts of semi-bleached petrolatum).
Suspend at a ratio of 1 g of powder per 00 g. Using the test conditions of Example 1 with small plates of non-alloyed steel with 0.32% carbon and rings of case hardened and tempered 16NC6 steel, the coefficient of friction in the presence of the above lubricant was 0.016 and the same If pure petrolatum was used under these conditions, the friction coefficient would be 0.12, and if the same oil was added with 1% graphite, the friction coefficient would be 0.07.

[Brief explanation of drawings]

Figure 1 is an equilibrium diagram of the iron-molybdenum-sulfur ternary system.

Claims (1)

[Scope of Claims] 1. An anti-friction alloy consisting of iron, molybdenum and sulfur which exhibits extremely low coefficient of friction throughout the material even in a dry state, the weight composition of these components being iron 8.0-26. .6%, molybdenum 41.0-62.5%
, sulfur in the range of 23.3-40.5%, Fe_xM
o_3_+_yS_4 (where x does not include 0 and is less than or equal to 1, and y is from 0 to less than 1), containing at least one kind of dispersed phase in the crystalline base material, and under the effect of friction with the other material. An anti-friction alloy characterized in that it is suitable for reacting with and forming a corresponding sulfide on the surface of its counterpart. 2. The anti-friction alloy according to claim 1, wherein the crystalline matrix corresponds to the composition of FeMO_4S_5. 3. The anti-friction alloy according to claim 1, wherein at least FeMo_2S_4 is dispersed in the matrix. 4. The anti-friction alloy according to claim 1, wherein at least FeS is dispersed in the crystalline matrix. 5. The anti-friction alloy according to claim 1, wherein at least Fe is dispersed in the crystalline matrix. 6 At least ε phase in the crystalline matrix: FeMo
The anti-friction alloy according to claim 1, wherein _2 is dispersed. 7. Anti-friction alloy according to claim 1, in which the proportion of Mo is at least 55.0% by weight.